1. Field of the Invention
The present invention relates to a liquid crystal display device having a liquid crystal display panel which sandwiches a liquid crystal layer between a pair of substrates, and more particularly to the stacked structure of an organic resin film on a peripheral portion between a pair of substrates which is arranged to face each other in an opposed manner.
2. Description of the Related Art
A liquid crystal display device having a liquid crystal display panel is an image display device which is basically configured by sealing a liquid crystal layer between two substrates consisting of a first substrate and a second substrate preferably formed of a glass substrate respectively, and performs a display by making use of change of alignment direction of liquid crystal in response to an electric field applied to liquid crystal from pixel selection electrodes formed on the substrate. A whole-transmissive-type liquid crystal display device which has been popularly used currently adopts the structure in which a light-source light projected from a backlight mounted on a back surface of a liquid crystal display panel is polarized in the liquid crystal layer at an approximately 90 degrees and an electronic image is observed as a visible image by allowing the polarized light to pass through a polarizer.
FIG. 12 is an enlarged cross-sectional view of an essential part of a sealing portion for explaining one example of the constitution of a liquid crystal display panel which is applied to this type of color liquid crystal display device. Further, FIG. 13A to FIG. 13C are schematic constitutional views of an essential part showing the constitution in FIG. 12, wherein FIG. 13A is a cross-sectional view of the sealing portion in FIG. 12, FIG. 13B is a plan view of an essential part of an upper glass substrate in FIG. 13A as viewed from an inner surface side, and FIG. 13C is a perspective view of an essential part in FIG. 13B. In FIG. 12 and FIG. 13A to FIG. 13C, the liquid crystal display panel 100 includes a light-transmitting glass substrate 1 and the light-transmitting glass substrate 2.
On a display region 10 of the glass substrate 1, pixel electrodes 11 made of ITO or the like and thin film transistors 12 which constitute switching elements are arranged in a matrix array. A protective film 8 made of silicon oxide, silicon nitride or the like is formed on a whole upper surface of the glass substrate 1 in a state that the protective film 8 covers the pixel electrodes 11 and the thin film transistors 12. Further, an alignment film 7b made of polyimide, for example, is arranged on an upper surface of the protective film 8 within the display region 10, for example. In the drawing, numeral 10′ indicates a non-display region.
Further, on the display region 10 of the glass substrate 2, a black matrix film 3 made of a resin material or the like is formed in a grid array, and respective color filters 4 consisting of red color filters, green color filters and blue color filters are arranged in respective grids. Further, a common electrode 6 made of ITO is arranged below the respective color filters 4 by way of an overcoat film 5. Here, the black matrix film 3 is formed between the red, green and blue color filters 4. Further, also on the boundary portion between the display region 10 and the non-display region 10′, a black matrix film 3a is formed. Further, an alignment film 7a made of polyimide is arranged below the common electrode 6.
Further, the glass substrate 1 and the glass substrate 2 are adhered to each other by way of a sealing material 9 formed by printing on the non-display region 10′ on a predetermined surface of either one of glass substrates 1, 2 and made of an epoxy resin material or the like containing spacers SP. To focus on a glass-substrate-2 side on which the color filters 4 are arranged, the sealing material 9 is adhered to an upper surface of the overcoat film 5. Further, a liquid crystal layer LC is sealed between an alignment film 7a and an alignment film 7b of both glass substrates arranged inside the sealing material 9. Further, the black matrix film 3a formed on the non-display region 10′ is provided for preventing leaking of light from a periphery of the display region 10.
With respect to a liquid crystal display panel of this type, patent document 1 (Japanese Patent Laid-open Hei 10-170930) discloses the structure in which two electrode substrates are adhered to each other by way of a sealing material, an inner peripheral portion of the sealing material is made to overlap the black matrix film formed in a frame shape outside the display region, and an outer peripheral portion of the sealing material which does not overlap the black matrix film is directly adhered to the electrode substrate thus preventing leaking of light from an end portion of the black matrix film.
Further, with respect to another liquid crystal display panel of this type, patent document 2 (Japanese Patent Laid-open No. 2002-090719) discloses the structure in which outer end portions of two electrode substrates are laminated to each other by way of a sealing material, a first black matrix film is formed on the electrode substrate, and a second black matrix film is formed at a position where the second black matrix film overlaps the first black matrix film and does not overlap a display region thus suppressing leaking of a backlight light from a gap formed between the liquid crystal display panel and a metal frame.
Further, with respect to still another liquid crystal display panel of this type, patent document 3 (Japanese Patent Laid-open No. 2004-294799) discloses the structure in which outer end portions of two electrode substrates are laminated to each other by way of a sealing material, and a periphery of a display region is shielded from a light using a black matrix film extending over a frame-shaped sealing portion thus preventing leaking of light from a region defined between the display region and the sealing portion and, at the same time, further effectively enhancing an adhesion strength of the electrode substrates at the sealing portion.